A really weird problem with querying a map

[Gregor Mosheh]

Fawcett, David wrote:
> I wasn't trying to imply that the best solution was to 'pre-project'
> your data.  I was just trying to figure out if the issue was in the
> projection code or the tolerance code.  (could be both I guess)

Understood.


> Have you tried displaying both a layer in the original SRS (projected
> on-the-fly) and your pre-projected data layer?

Actually, yes. I had the one query layer reprojected, and all others at 
geographic. At this time, map alignment was still A-OK, same as it was 
when all layers were geographic and the map's output was 26709. 
Therefore, reprojection for map generation seemed to work just fine.

The issue seems to be in reprojecting from map SRS to layer SRS when 
querying.


Unfortunately, the customer has now signed off on the map, using all 
data in the same SRS, so I am no longer able to work on that map.

To reiterate for a bug report:

* This was under 4.10.3 Perhaps it has already been fixed in 5.0 ?
* The map output was EPSG:26709 and the layers were all EPSG:4269 
(geographic nad27). All layers were of contiguous polygons.
* The only way queries would work under those conditions was to use a 
very large buffer (1000 pixels), and making the buffer smaller seemed to 
cause the hits to become looser, hitting neighboring polygons. A buffer 
of 0px caused queries to always fail, rather than the intended behavior 
of a click matching only inside the polygon.
* Changing the layer to 26709 solved the problem entirely.

-- 
Gregor Mosheh / Greg Allensworth
System Administrator, HostGIS cartographic development & hosting services
http://www.HostGIS.com/

"Remember that no one cares if you can back up,
  only if you can restore." - AMANDA